restore tab completion behavior

this is a minimal patch to restore proper tab completion behavior, a
partial revert of  #8355. I think avoiding the explicit poking into the
__bases__ classes address the concerns  #8330.

IPython/utils/dir2.py

@@ -1,81 +1,84 b''
 # encoding: utf-8
 """A fancy version of Python's builtin :func:`dir` function.
 """
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 import inspect
 from .py3compat import string_types
 
 
 def safe_hasattr(obj, attr):
     """In recent versions of Python, hasattr() only catches AttributeError.
     This catches all errors.
     """
     try:
         getattr(obj, attr)
         return True
     except:
         return False
 
 
 def dir2(obj):
     """dir2(obj) -> list of strings
 
     Extended version of the Python builtin dir(), which does a few extra
     checks.
 
     This version is guaranteed to return only a list of true strings, whereas
     dir() returns anything that objects inject into themselves, even if they
     are later not really valid for attribute access (many extension libraries
     have such bugs).
     """
 
     # Start building the attribute list via dir(), and then complete it
     # with a few extra special-purpose calls.
 
     try:
         words = set(dir(obj))
     except Exception:
         # TypeError: dir(obj) does not return a list
         words = set()
 
+    if safe_hasattr(obj, '__class__'):
+        words |= set(dir(obj.__class__))
+
     # filter out non-string attributes which may be stuffed by dir() calls
     # and poor coding in third-party modules
 
     words = [w for w in words if isinstance(w, string_types)]
     return sorted(words)
 
 
 def get_real_method(obj, name):
     """Like getattr, but with a few extra sanity checks:
 
     - If obj is a class, ignore its methods
     - Check if obj is a proxy that claims to have all attributes
     - Catch attribute access failing with any exception
     - Check that the attribute is a callable object
 
     Returns the method or None.
     """
     if inspect.isclass(obj):
         return None
 
     try:
         canary = getattr(obj, '_ipython_canary_method_should_not_exist_', None)
     except Exception:
         return None
 
     if canary is not None:
         # It claimed to have an attribute it should never have
         return None
 
     try:
         m = getattr(obj, name, None)
     except Exception:
         return None
 
     if callable(m):
         return m
 
     return None